Fig. 4

Precision neuronal modulation and controlled neuronal growth. a Schematic illustration of neuronal modulation and growth via optomechanical bio-dart with precision down to subcellular neuronal structures. Inset shows the activation of intracellular molecular pathway for increased ATP generation after dart stimulation. b Intracellular ATP response of a target HT22 cell after stimulation with dart. Panel I: bright field image showing dart stimulation of a target cell. Panels II, III: fluorescent images showing ATP response. Microscopic images showing precision modulation and short-term growth of subcellular neuronal structures (c) dendrite, (d) axon, and (e) soma. Red arrow indicates the direction of dart shooting, yellow arrow indicates the position of dart on target position of a neuronal cell, red curves on cell boundary shows the outgrowth of target cell. Microscopic images show long-term growth of target single neuronal cell after stimulation by dart with different velocities of (f) 30 µm s⁻¹ and (g) 120 µm s⁻¹. Red curves show the boundary of target cell with stimulation, while white curve shows the neighboring cell without stimulation. h Fluorescence intensity of ATP signal as a function of time after stimulation of soma. i Growth length of intracellular neuronal structures of HT22 cell as a function of time after stimulation. j Long-term growth length of HT22 cell as a function of time for dart stimulation with different velocities. Blue region indicates stationary phase of neuronal cell growth. k Average growth length as a function of stimulation interval for two different neuronal cell types. Scale bars: 20 µm. The statistical data in h–k are concluded based on 20 cell repeats, the error bars are standard error of the mean